The invention relates to arrangement of at least one induction coil for inductively charging an energy accumulator on an underbody of a motor vehicle.
Induction coils of this type are particularly readily suitable for contactless charging, for example, of a vehicle battery (energy accumulator), wherein all that is required is to place the motor vehicle for a relatively long period of time over a charging device emitting a changing magnetic field, in order to charge the energy accumulator. Charging devices of this type can be provided, for example, in public car parks, wherein defined parking times of motor vehicles equipped with such an induction coil are used in order to charge the energy accumulator (vehicle battery) while the motor vehicle is parked. Specifically in comparison to the refueling operation when refueling motor vehicles with fossil fuels, advantages then arise to the effect that no special gasoline station has to be found in order at least partially to fill the energy accumulator, and also to the effect that the charging of the energy accumulator takes place in a contactless manner and, accordingly, can proceed particularly ergonomically and without further action by the driver. Furthermore, specifically in contrast to refueling with fossil fuels, during the refueling operation or during the charging of the energy accumulator no fuel vapors are released and, accordingly, a particularly large contribution is made to environmental protection or to protection of health. For example, it is known that hydrocarbon compounds customarily released during the refueling operation with fossil fuels may rise in the form of gasoline vapors or diesel vapors, wherein vapors of this type can be classified as environmentally harmful or carcinogenic.
The induction coil, which is arranged on the underbody, of motor vehicles of this type designed for inductive charging is also referred to as a “secondary coil” or as a “car pad module (CPM)”. If the motor vehicle is now parked over a charging device for inductively charging the energy accumulator of the motor vehicle, a “primary coil” of the charging device is brought up to the secondary coil, which secondary coil is arranged on the underbody of the motor vehicle, and is oriented relative to the secondary coil. A magnetic field that changes at a defined frequency is built up by means of the primary coil. By way of this changing magnetic field and with the interposition of the secondary coil, the energy accumulator (vehicle battery or high voltage battery) of the motor vehicle is charged. The closer the primary coil is brought up to the secondary coil of the motor vehicle, or the more exactly the primary coil is oriented relative to the secondary coil, the more efficient is also the charging operation.
It is the object of the present invention to provide an arrangement of the type mentioned at the beginning, in which an efficient charging operation is made possible even in the event of an increased distance between the secondary coil and the primary coil, and in the event of a less exact orientation of the primary coil relative to the secondary coil.
This and other objects are achieved by an arrangement of at least one induction coil for inductively charging an energy accumulator on an underbody of a motor vehicle, wherein the induction coil is at least partially covered on a downward side in the vertical direction of the vehicle by at least one covering element.
In order to provide an arrangement, by which effective charging is permitted even with an increased distance or less exact orientation of the primary coil relative to the second coil, it is provided according to the invention that the induction coil is at least partially covered on a downward side in the vertical direction of the vehicle by at least one covering element.
It can be avoided by means of the covering element that the induction coil of the motor vehicle, i.e. the secondary coil, is damaged while traveling. Such damage may otherwise occur, for example, due to an external action on poor sections of a road, or from relatively large amounts of spray water (or salt-containing water in winter) that reaches the electronic components, such as the induction coil. Therefore, the covering element avoids damage to the induction coil or disadvantageously affecting or impairing the stray field of the induction coil as a consequence of, for example, the impact of objects, such as stones or branches striking against the underbody of the vehicle. The efficiency during charging of the energy accumulator (high voltage battery, battery) can therefore be maintained particularly substantially over the service life of the vehicle by the covering element since possible damage or effects of spray water on the induction coil is effectively prevented by use of the covering element.
The covering element can be formed, for example, from a glass fiber plastic, as a result of which the magnetic field is minimally disturbed during the inductive charging although the covering element is arranged between the induction coil (secondary coil) of the motor vehicle and the primary coil. The efficiency of the charging operation can even be further improved by, for example, a field-guiding region with respective field-guiding elements being arranged on the covering element, wherein said field-guiding elements correspond to “ferrites”. For example, a defined region (field-guiding region) of the covering element is designed to a particular extent to orient the magnetic field in an optimum manner in terms of efficiency during the inductive charging, wherein, in addition to the magnetic field, an electric field which is associated with the buildup of the magnetic field is also positively influenced. However, the covering element may also be used for the merely partial covering of the induction coil of the motor vehicle and may have, for example, an open frame region into which the primary coil is inserted during charging and is locked, i.e. oriented, par rapidly and exactly relative to the induction coil of the motor vehicle. This leads to the inductive charging being able to take place particularly rapidly and, accordingly, particularly large savings on time can be obtained since an orientation aid for the orientation of the primary coil is provided by the open frame. When the induction coil is partially covered by the covering element, i.e. for example, by using such an open frame, which then, for example, protrudes downward beyond the induction coil, i.e. toward the contact area of the motor vehicle, the impact of damaging objects or a possible action of spray water on the induction coil of the motor vehicle can be at least substantially prevented, wherein, at the same time, the primary coil can be oriented particularly rapidly with respect to the secondary coil.
Further advantages, features and details of the invention emerge from the description below of a preferred exemplary embodiment and with reference to the drawings. The features and combinations of features mentioned above in the description and the features and combinations of features which are mentioned below in the description of the figures and/or are shown solely in the figures are usable not only in the respectively stated combination, but also in other combinations or on their own without departing from the scope of the invention.